Various compounds and methods have been investigated for use in producing an amino acid-modified or a peptide-modified silicone and for use in its production method.
For example, in the case of a silicone modified with an amino acid derivative represented by the following formula:
the silicone has a structure in which the amino group and the carboxy group of the amino acid have been protected. In addition, this silicone has been produced by using various toxic compounds such as isocyanate and dicyclohexyl carbodiimide, and this is unfavorable in view of safety. Furthermore, the compound having such complicated structure can not be produced by a simple procedure (JP-A 2004-182680).
A silicone modified with an amino acid derivative represented by the following formula:
also suffers from the problem that it is produced by using a protected amino acid derivative whose synthesis not easy (JP-A 2004-269459).
A peptide-silicone copolymer represented by the following formula:
has been produced by a method using generation of polysuccinimide from aspartic acid. However, this method is dangerous since a temperature as high as at least 160° C. is required. In addition, unnecessary components are generated by side reaction, and this leads to the need of filtration and washing as well as low yield (JP-A 2000-143797).
JP-A H3-223207 discloses a method in which a silicone having one epoxy-modified end is reacted with the amino group of a peptide. However, this method is unfavorable since the epoxy-modified silicone used as the reactant is toxic.
JP-A H11-286550 discloses hydrolytic copolymerization of a peptide-containing silane with an alkoxysilane or the like. This method, however, suffered from the problem of insufficient storage stability since the amino group and the carboxyl group from the peptide-containing silane formed —Si—NH— and —Si—OOC— which are less resistant to hydrolysis.
For the organosilane compounds, JP-A H8-59424 discloses a polypeptide-containing silane as a compound having both the amino group and the carboxyl group introduced in one molecule. For the amino acid-modified silane compound, JP-A 2002-146011 and JP-A 2003-160663 disclose an amino acid group-containing silane produced by reacting an amino functional silane and an α-amino acid-N-carboxylic acid anhydride. The compound disclosed in the JP-A H8-59424 is a compound having a polypeptide bonded to the silane and not a compound constituted by the monomeric amino acid units linked together. This compound also has the problem of toxicity due to its use of epoxy-modified silane. The amino acid group-containing silane disclosed in the JP-A 2002-146011 and JP-A 2003-160663 is the one produced from an α-amino acid-N-carboxylic acid anhydride and an amino-modified silane, and the α-amino acid-N-carboxylic acid anhydride is very expensive, and has the problem that it is not readily available in the commercial market.
In view of such situation, a novel amino acid-modified silane which can be produced from highly safe starting materials in a convenient manner at a high yield is highly awaited. In addition, an amino acid-modified silane synthesized from an amino-modified silane and a pyroglutamine acid derivative is still unknown in the art.
Furthermore, JP-A H11-140032 discloses production of a N-long chain acyl acidic amino acid by reaching an acidic amino acid with a fatty acid halide as a derivative having a long chain alkyl group or a fatty acid bonded to the amino acid. JP-A S63-301854 discloses production of a neutral amino acid —N-carboxylic acid anhydride by using phosgene. JP-A 2000-44554 discloses a production method of an amino acid anhydride as well as a production method of its derivatives. In the case of the amino acid group-containing compound disclosed in the JP-A H11-140032, the hydrophilic group in the resulting product would only be the carboxyl group since the amino group is reacted with the acid chloride. The compound also suffers from the problem of the chlorine compound generated from the fatty acid chloride remaining in the resulting product. The amino acid group-containing compounds disclosed in JP-A S63-301854 and JP-A 2000-44554 are unsafe due to the use of phosgene in their production, and the production cost is also high.
By the way, the method of bonding an aliphatic amine, a higher aliphatic amine, or a hydroxy aliphatic amine with an pyroglutamine acid derivative through amide bond, and the an amino acid group-containing compound having both the amino group and the carboxyl group as the hydrophilic groups produced by such method are unknown in the art.
In view of such situation, a strong need exists for the development of a novel amino acid group-containing compound which has a hydrocarbon group as the lipophilic group and carboxyl group and amino group as the hydrophilic group, and which can be produced from highly safe starting materials in a convenient manner at a high yield.